POSITIVE PREDICTIVE VALUE OF BREAST BIOPSY PERFORMED AS A RESULT OF MAMMOGRAPHY - THERE IS NO ABRUPT CHANGE AT AGE 50 YEARS

PURPOSE: To determine if the positive predictive value (PPV) of a biop sy initiated because of an abnormal mammogram changes abruptly at age 50 years. MATERIALS AND METHODS: The PPV and its variation with age wa s analyzed for 4,778 women who underwent biopsy for a clinically occul t abnormality detected at mammography. The relationship of the results to the patient's age was analyzed with age represented as a continuou s and two-categoried (< 50, > 50) measure. The latter measure represen ted an abrupt change, which distinguished those aged 49 years and youn ger from those aged 50 years and over. With this measure, the patients in each of the two age groups were statistically indistinguishable. R ESULTS: The results were consistent with a steady increase in PPV and the yield of cancers with age, and there was no abrupt change at age 5 0 years. The modeled PPV for all cancers for these 4,778 patients was approximately 12% for women aged 40 years and increased to 46% by age 79 years. CONCLUSION: The PFV did not change abruptly at any age for w omen aged 40-79 years but increased steadily, which reflects the prior probability of breast cancer at each age. Inappropriate grouping of d ata can lead to misinterpretation of results. Screening guidelines sho uld not be predicated on the false assumption that this variable chang es at age 50 years.